But Mr. Arnold admits that he is engaging in some racial profiling himself these days, casting a wary eye on men who look to be of Middle Eastern descent. If he saw a small knot of such men boarding a plane, he said: ''I'd be nervous. It sickens me that I feel that way, but it's the real world.''

Adrian Estala, 27, a risk-management consultant in Houston who is Hispanic, is struggling with the same emotions. Mr. Estala is ''absolutely against'' racial profiling, he said, because it a fundamental violation of liberty. But asked about sharing an airplane flight with Arab-looking men, he said he would be anxious.

''Absolutely I have to be honest,'' Mr. Estala said. ''Yes, it would make me second-guess.''

On the other side of the divide, Arab-Americans find such views offensive. ''Think what it really means,'' said Nadeem Salem, a second-generation American who leads the Association of Arab-Americans in Toledo, Ohio. ''People's civil liberties are being tarnished, compromised. That's not what this country is all about.''

For many Americans who say they have deeply believed that it was wrong for law enforcement officers to single out members of minorities for special interrogation or searches, the terrorist attacks on Sept. 11 have prompted a painful confrontation with the sudden anxieties they acknowledge feeling in the presence of one minority in particular. With all of the hijackers involved believed to have Arab backgrounds, these Americans say, officials have ample reason to zero in on that group. ''It's not right,'' said Virginia Hawthorne, a retired accountant from Bremerton, Wash., ''but it's justified.''

Such sentiments seem to have been in play on Thursday in Minneapolis when three Middle Eastern-looking men were denied permission to board a Northwest Airlines flight after several passengers complained of their presence, an airline spokesman said. The men were later permitted to take a Delta flight.

While expressing regret at what they portrayed as the need for more detailed interrogations of people of Arab background, many people said the subjects should understand and accept it.

''They shouldn't be offended,'' said Leslie Brenaman, a retired Boeing graphics designer, who is white. ''They shouldn't take it personally after what's happened.''

Wali Khairzada, owner of Kabul Afghan Cuisine here, said he felt heartsick about a decision he made the other day: not to take his father-in-law, who is German, to the airport for his flight home.

''It makes me feel sad, but I feel I should stay away,'' said Mr. Khairzada, who came to this country in the late 1970's and became an American citizen in 1986. ''I would be checked there far more thoroughly than the average person.''

On the other hand, he added, he had been buoyed by racial profiling of a different sort in recent days. ''So many people have come in to the restaurant to offer some support,'' Mr. Khairzada said. ''I'm amazed, I'm grateful, I'm flabbergasted.''

Ashraf Khan, 32, a mobile phone salesman from New Braunfels, Tex., who was ordered off a Delta Airlines flight from San Antonio on Monday while bound for his brother's wedding in Pakistan, said he was distressed by the pilot's action, which the airline said it was investigating. Delta offered a later flight, but by that time Mr. Khan had missed his connecting flight and the wedding.

''I am really depressed about the whole situation,'' he said, ''the way they've treated me, like I'm some sort of criminal.''

In interviews around the country, many people expressed revulsion at the spate of attacks on Muslims, as well as on Hindus and Sikhs, and the vandalism at mosques. Those interviewed spoke of national ideals of colorblindness -- but in nearly the same breath they said that for the sake of national safety, the police should single out Arab-looking men for questioning.

Kathy Komlance, 43, who was wearing an American flag T-shirt as she worked at a taffy stand at the Mid-South Fair in Memphis, said she favored checking their credentials. ''I think a person who is Arab should be questioned if they get on a bus or plane or go in a government building,'' Ms. Komlance said. ''You don't want to be afraid of Arabs, Iranians or other foreign people. But how do you differentiate and figure out which one is the bad one from those who love freedom and our country?''

A CNN/USA Today/Gallup poll taken a few days after the attacks showed that Americans were supporting special measures intended for those of Arab descent. In the survey, 58 percent backed more intensive security checks for Arabs, including those who are United States citizens, compared with other travelers; 49 percent favored special identification cards for such people, and 32 percent backed ''special surveillance'' for them.

In the interviews, many people said they hoped the need for the sort of racial profiling they favored would be temporary, while others were firmly against racial profiling and said there was no justification for it.

''They should interrogate everybody the same way,'' said LaVonne James, a Seattle parks department worker. ''I mean, at airports, they should stop everybody the same way, search luggage, ask all the questions. You just don't know. That little old grandma from Sioux City could be carrying something.''

Others made a strong distinction between thinking and acting.

Tina Wells, 19, a shoes saleswoman here, said ''there might be a little inkling in my mind'' if she saw a group of Arab-looking men together.

''But I'd just get past it, as quickly as possible,'' Ms. Wells said. ''I wouldn't change the way I behaved. I wouldn't not get on an airplane. It would just be wrong.''

And some said they were going out of their way to be friendlier than ever to Arab-Americans. Sasha Nyary, who works for a community development organization in Brooklyn and is the mother of a daughter, Lily, 2, said she was seeking out a mosque and Arab-owned businesses.

''There are a couple of ways I can walk to get to Lily's school at Third Avenue and Atlantic,'' Ms. Nyary said, ''and this week I've deliberately chosen to go down the south side of Atlantic so I can maximize the number of Arab shopkeepers I see.''

Many people who belong to minorities said they felt especially torn by their newfound acceptance of at least one form of racial profiling.

''I've seen prejudice all my life, with me growing up as an African-American male,'' said Jermaine Johnson, 19, a business management student at Southwest Tennessee Community College in Memphis. ''I try not to judge.''

But Mr. Johnson added: ''I would not feel comfortable at all if an Arab-looking person sat next to me on a plane. I would be nervous, I mean right now it could be anyone and that's not good if they sit next to you on a plane. I don't feel comfortable with the ones I don't know. It's hard to know who to trust.''

Others said they were consciously trying to put aside any snap judgments based on race.

''I think it's just wrong to do anything like that, even with what's happened,'' said Viridiana Chaveste, 18, a cleaner at Seattle's Safeco Field who is Hispanic.

Her friend Karen Calderon, 20, agreed. ''Honestly, thoughts would go through my head,'' she said when asked how she would react to seeing a group of Arab men on the street or in at airport departure gate. ''But I wouldn't do anything about it. I wouldn't treat them any differently.''